Calculating Net Force on a Point Charge in a 2D Coulomb's Law System

[cobhc27]

Homework Statement

Consider the arrangement of point charges shown below. Calculate the net force on point charge 1 given the arrangement of the point charges and the separation of the charges.

1=2=3=e-
2=e+
r=0.4cm
=0.0004m
K=9x10^9
Fnet=?

Please use this link for an image of the "point charges shown below"
http://i277.photobucket.com/albums/kk71/cobhc_27/physics101.jpg

Homework Equations

Fnet=
Kq1q2
r^2

The Attempt at a Solution

Fnet=
Kq1q2
------
r^2

=
kq^2
-----
r^2

I assume you have to solve for 1 2 3 and 4 in this case, but I don't have a great idea on how to. From there, perhaps you add up each net force (but I don't know how to incorporate the 2d part). Any help given is greatly appreciated.

 

[Knissp]

From there, perhaps you add up each net force (but I don't know how to incorporate the 2d part

Remember that force is a vector. To add vectors (in two-dimensions or in n-dimensions), add the components of the vector. The components can easily be calculated using trigonometric ratios, especially since you know the angle.

1=2=3=e-
2=e+

Could you clear this up a bit? You have 2 twice.

 

[Fredrik]

It's pretty easy:

1. Calculate the force on 1 caused by 2.
2. Calculate the force on 1 caused by 3.
3. Calculate the force on 1 caused by 4.
4. Add the forces together.

Do you know how to calculate the distance between 4 and 1? Do you know how to add vectors?